With the expansion of European colonialism from the Early Modern era, Western Christianity spread throughout the Americas, much of the Philippines, Southern Africa, pockets of West Africa, and throughout Australia and New Zealand. Thus, when used for historical periods after the 16th century, the term "Western Christianity" does not refer to a particular geographical area, but is rather used as a collective term for the Catholic Church, the Protestant denominations, and the other forms of Christianity that trace their lineage to Western Europe.

Today, the geographical distinction between Western and Eastern Christianity is not nearly as absolute as in Antiquity or the Middle Ages, due to the spread of missionary activities, migrations, and globalisation. The adjectives "Western Christianity" and "Eastern Christianity" are typically used to refer to historical origins and differences in liturgy, rather than present geographical locations.

For most of its history the church in Europe has been culturally divided between the Latin-speaking west, whose centre was Rome, and the Greek-speaking east, whose centre was Constantinople. Cultural differences and political rivalry created tensions between the two churches, leading to disagreement over doctrine and ecclesiology and ultimately to schism.